The objective of the project is to obtain full length genomic DNA clones and cDNA clones for both the alpha and beta-chains of the functionally important cell surface antigen, MAC-1, and to characterize these clones in detail. The complete DNA sequence of the cDNA clones will be determined and from this the protein sequence of MAC-1 deduced. Extensive studies on the relationship between structure and function of the protein will be undertaken using a variety of mutagenesis protocols. Mutants in the protein will be assayed for function using a very efficient protocol based upon an easily rescued retrovirus vector. The promoters for both MAC-1 genes will be mapped on the genomic clones and further characterized by genetic analysis. Changes in the level of methylation of the gene and of the DNAse reactivity of the gene's chromatin will be studied as a function of macrophage differentiation. Proteins which bind to the genes control region will be characterized by Crothers' gel analysis.